(1) On any envelope where the elector's signature and the signature of the attesting witness are required, the signature lines and the signatures shall be in the boxes across the flap of the envelope to ensure the integrity of the ballot and the following shall be printed on the flap on the back of the envelope in bold print and in a distinguishing color: "YOUR VOTE WILL BE REJECTED AND NOT COUNTED IF THIS ENVELOPE IS NOT SIGNED BY YOU AND AN ATTESTING WITNESS IN THE BOXES ACROSS THE FLAP OF THIS ENVELOPE ." A portion of the elector's signature extending outside of the box shall not be grounds for rejecting that elector's ballot.